I've been very happy with my preferred driver tube these days, Philips SQ 7062. These have the ideal combination of openness, warmth and intermediate gain which do not drive fast and sensitive output tubes (like the current production Tung-Sols), into sibilance on very high frequency passages. As opposed to 12AT7's, these drivers need an open, big sounding output tube to sound their best though.

On third place, the Brimars with the Russian Reflektor Plant black glass 6V6's. The usually dark but sweet sounding Russians need to be opened by a powerful, commanding driver, and the Brimars are just the ticket.

The Tung-Sol 6V6's are good tubes but can be ridden to far on high frequency passages by 12AT7's in the M-T. My Phillips SQ 7062's do not show special synergy with these (like with my G ST's), although the combination sounds fine nevertheless.

In all the above suggested combos, I use the RFT EZ80 rectifier rather than the stock JJ EZ81 (not only due to reliability issues).

Some time ago, I decided to skip any output tube outside the 6V6 family due to potentially excessive stress on the circuit and because IMO the original voicing enhances the 6V6. YMMV.

My next test will be a pair of 6414's paired with my tour de force RCA's G ST's. I've heard good things about these drivers and according to the literature, these are very similar to the 7062's.

In general, I prefer to go for drivers offering an intermediate gain between 12 AU7's and 12AT7's, as the former are somewhat dull-sounding in the M-T, whereas the latter tend to be edgy in the high frequency ranges.

The 6V6 G ST's sound big, with wider soundstage, PRAT and transparency, and as has been mentioned here, its bass is better than the rest of my other combos with the ubiquitous OA3's in place. My OD3's, on the other hand, flatten that sound, killing some of the presentation depth.

Yet, the biggest sound improvement from my system came from the installation of 7 DIY absorption pannels, critically placed in the room. There's no question reflections kill the soundstage and naturalness of the sound, and increases listening fatigue. Today, at close to near field, my system behaves neatly and timbres and imaging are again in focus, while bass lines are deeper and well defined (as opposed to boomy).

My system uses an active subwoofer with a crossover at 65Hz and thanks to the absorption pannels now the bass really enhances the nice low-mids, mids and highs of the DM945's when placed on monitor stands and away from walls.

Interested in anyone's experiences with 6414's and the corresponding best output tube pairing.

A NOS 12AU7 to replace the stock JJ 12AU7 (I was lucky that my Mini Torii stock tube was a NOS RCA 12AU7 (I did obtained a stock JJ 12AU7 for a comparison). Cost from $20.00 per pair to $100.00+ per pair).

Try to replace the stock JJ EZ81 for a NOS EFT, Mullard or Amperex (you may just wait for the JJ EZ81 to fail, it will not take very long). NOS EFT EZ81 on ebay for $25.00 per pair

"For most applications calling for a 7581, KT66, or 6L6GC these tubes will work fine and sound great. They do have different filament current draw specs and other slight differences, so you should always check with the amp manufacturer, dealer, or a tech before subbing these tubes in place of the stock tubes."

The 350's (A & B) seem to be considered the best sounding in this tube family. I just wonder if we can use the KT66's safely in the Mini Torii and if the amp's voicing is consistent with their characteristics ... I assume the latter holds as per the recommendations.

Individual good tubes may or may not be special, depending on the accompanying complement set. SQ 7062's are not that special if paired with Tung-Sol, JJ or Reflektor Plant 6V6's, in my experience. YMMV.

I found the difference btw the RCA 6v6g st and the VA350's to mainly one of bass. Your description of the 350's is right on, we differ only the lower end. The 6v6g's just seem to have more punch in relationship to the 350's

It may be that i'm new to low watt and more used to bigger pumpier tubes like kt88's and el34's

In case you are interested, I bought the RCA G ST's from Brent Jesse ($50.00 matched pair). When later I asked him for an additional pair as back-up, he said he was out of them. He said he will make a buying trip early January and he'll probably get them, so I'm holding my order of those plus the 6414's which seem to be another good driver alternative.

I absolutely agree with Grinnel's description of the G ST's and so far the 7062's seem to make the best out of them. Although there could be 12AU7's with some special synergy, I have not been lucky with reasonably priced 12AU7's in the Mini Torii.

Good 12AT7's paired with darker (warm) sounding 6V6's are another good combination IMHO.